Shear cut perforator

ABSTRACT

This disclosure relates to a web perforating apparatus. Essentially the apparatus includes an unwind stand for supporting and unwinding a web of material, whether it be paper, foil or plastic, which is fed over a large rotating roll carrying circumferentially spaced rows of knives or blades which extend beyond the surface of the roll. A stationary rigid beam, coextensive with and adjacent the roll, support blocks mounting anvil blades or knives embedded in or surrounded by elastomeric material. The anvil knives make contact with the roll knives to effect perforation of the web.

United States Patent 191 Aterianus Nov. 13, 1973 SHEAR CUT PERFORATOR[75] Inventor: John S. Aterianus, Green Bay,

Wis.

[73] Assignee: FMC Corporation, San Jose, Calif.

[22] Filed: Oct. 6, 1970 [21] Appl. N0.: 78,533

[52] US. Cl. 83/348, 83/674 [51] Int. Cl B27d 25/12 [58] Field of Search83/346, 347, 348, 83/426, 508,542, 592, 673, 674, 698, 349, 658, 583

[5 6] References Cited UNITED STATES PATENTS 2,986,058 5/1971 Besserdich83/348 1,977,283 10/1934 Lundquist... 83/347 3,521,514 7/1970 Fiezell l83/347 844,171 2/1907 McAnulty... 83/348 2,341,503 2/1944 Bombard 83/3233,196,724 7/1965 Frank 83/583 X Primary Examiner-Andrew R. JuhaszAssistant Examiner-Leon Gilden Attorney-F. W. Anderson, C. E. Tripp andL. J.

Pizzanelli ABSTRACT This disclosure relates to a web perforatingapparatus. Essentially the apparatus includes an unwind stand forsupporting and unwinding a web of material, whether it be paper, foil orplastic, which is fed over a large rotating roll carryingcircumferentially spaced rows of knives or blades which extend beyondthe surface of the roll. A stationary rigid beam, coextensive with andadjacent the roll, support blocks mounting anvil blades or knivesembedded in or surrounded by elastomeric material. The anvil knives makecontact with the roll knives to effect perforation of the web.

4 Claims, 22 Drawing Figures PATENTEUNUVUISB 3.771.399

sum 1 BF 5 IE'IG I INVENTOR. N JOHN s. ATERIANUS BY C. C:

ATTORNEY PATENIEDHUY 13 I975 SHEET l BF 5 FIIEI El FIEI E Fll3 ll:l FIl3l1 FIE IE FII3 ].=3

SHEAR CUT PERFORATOR BACKGROUND OF THE INVENTION New developments forperforating webs of paper, film or foil are shown and described in manypatents, both foreign and domestic. More recent patented developmentsare shown and described in U.S. Pat. Nos. 2,970,940 and 2,986,058. Thesedisclosures show apparatus for making transverse equally longitudinallyspaced perforations in a paper web derived from a large mill roll. Theperforations of the character made may be described as a series oflinear shear cuts and uncut web portions, sometimes referred to as tabs,extending transversely entirely across the web.

Web perforating apparatus can be associated with other apparatus such aswrappers, sheeters, bag machines, interfolders and towel or toilettissue rewinders. For convenience the present disclosure shows anddescribes the invention in connection with a rewinder which is sometimesreferred to as a winder. Winders comprise an unwind stand for rotatablysupporting a large parent or mill roll, controls for unwinding the webwith a desired tension, dictated by the character of the web and thetightness of the wind required, a perforating unit, core shaft handlingapparatus, mechanisms for feeding and mounting tubular paper cores onthe core shafts, and mechanisms for removing a consumer size roll, forexample toilet tissue or towelling, from the core shaft which is thenready for reception of another core. Accordingly, the perforatingmechanism of the character disclosed by the present invention iscombined with various other mechanisms to automatically produce consumersize rolls of toilet tissue or towelling.

The perforations performed by the apparatus of the present invention areknown by those skilled in the art as clean cut perforations. Suchperforations are achieved by providing stationary blades and rotatingblades which are mounted on a relatively large diameter roll, usuallyreferred to as a bed roll. The paper web is fed over the bed roll makingan arc of contact in the order of 140-170 degrees. As the bed rollrotates feeding the paper web through the winder the bed roll bladesmake point contact with the stationary blades which are slightly skewedfrom the roll axis to produce a progressive shear action extending fromone end of the blades to the other.

Perforating mechanisms operating on the shear cut principle provide thebed roll with generally rectangularly shaped blades or knives which arerelatively thin. The bed roll blades have one edge clamped to the bedroll and the opposite edge extending a short distance beyond the surfaceof the bed roll. The bed roll blade mounting may be best characterizedas a cantilevered beam which is subject to flexure or deflection when itmakes engagement with the stationary anvil blade. The bed roll isprovided with recesses or openings below the blade to allow for suchdeflection. It is usual practice to set the anvil blades and bed rollblades so that an interference of from three to six thousandths iscreated. With this interference flexure or deflection of the bed rollblades occurs during its engagement with the anvil blade.

Other perforating apparatus utilized with winders operate on theprinciple known as crush cut or pinch cut. Apparatus performing thismethod of perforation usually comprises two rotating rolls mountedadjacent each other. One roll has a smooth hardened surface and theother is provided with rows of circumferentially spaced chisel pointcutters which come in forceable contact with the surface of the smoothroll. The paper web is fed over the smooth roll, sometimes referred toas an anvil roll, bringing it in contact with cutters which maketransverse longitudinally spaced perforations in the web. For example,in the case of toilet tissue the perforations are usually made every 4%inches. The decided disadvantage of the crush or pinch cut perfora tionis that the anvil roll must assume massive propor tions to resist theforce of the perforating cutters which impose substantial shock forceswhich are necessary to perforate the web. This type of perforation canbe best characterized as piercing of a web supported on a solidfoundation by a sharpened element acting generally normal to the websupporting surface.

Machines performing the crush or pinch type of perforations have severelimitations the most prominent of which are the speed of operation andthe width that can be adequately handled by the machine. Theselimitations are a direct result of the general concept of forcing achisel tooth cutter through a web supported on a solid foundation. Toachieve the penetration forces required an interference setting must beestablished between the anvil roll and the blade roll. Accordingly,these forces, which ideally may be thought of as an evenly distributedforce applied to a beam of circular cross-section, cause deflection inthe beam and generate noise levels which are intolerable to operatingpersonnel and are destructive of the machine elements. Use of machineryperforming a crush or pinch cut is accordingly limited to approximately1,100 feet per minute and a maximum web width of 40 inches.

During the paper making process paper fibers accu mulate on parts of thepaper-making machinery which overlie the paper web. These fibersaccumulate much like snow drifts which fall in clusters on the paperweb. The clusters of fibers are eventually wound between wraps of themill roll. In the industry such accumulations of paper fibers are calledwads which are a normal condition encountered in all paper makingprocesses, particularly paper used for making toilet tissue andtowelling. When a mill roll of paper passes through a rewinder or winderthe wads obviously encounter the perforating unit and in doing so imposea burden on the perforating blades which oftentimes causes theperforator blades to break requiring shut-down of the machine.

The perforating unit shown in U.S. Pat. No. 2,986,058, assigned to theassignees of the present invention, mounts the stationary anvil bladeson anvil blocks which are mounted for a limited degree of rotation on atransverse shaft. The anvil blocks are held in their operative positionsby a spring force. In the event a wad or other condition interferringwith the perforating function of the blades occurs the anvil blocksmoves against the bias of the springs allowing passage of the wadwithout causing damage to the bed roll mounted perforating blades. Thepresent invention makes use of this advantageous feature since it mountsthe anvil blade in an anvil block of substantially the sameconstruction.

SUMMARY OF THE INVENTION In accordance with a primary feature of thepresent invention the rotating blades are mounted in the bed roll sothat deflection or flexure thereof does not occur when contact with astationary anvil blade takes place. Preferably all blade movement isaccommodated by the anvil blade which is associated with elastomericmaterial mounting the anvil blade in the anvil block.

Several distinct benefits result from such an arrangement. Since therotating blades carried by the bed roll are supported so that no flexureor deflection occurs, they can be heat treated to a higher degree ofhardness which therefore extends blade life and consequently thefrequency of adjustment is greatly reduced. Another advantage resultingin providing rigid blades in the bed roll is that the interferencesetting between the rotating and stationary blades made under staticconditions, or during low speed operation of the machine, will bemaintained during normal operating speeds which is in the order of from1,500 to 2,000 feet per minute. Perforators utilizing deflectible orflexible bed roll blades are bent outwardly relative to the radius ofthe bed roll blade due to the centrifugal forces. These forces obviouslyincrease proportionately with increases in the speed of the bed roll.

This condition greatly increases the difficulty and the time required toadjust the interference between the bed roll blades and the stationaryanvil blades. Most experienced operators perform the adjustment underrunning conditions by listening to the sound made when the bed rollblades make contact with the anvil blades. Therefore a fair'degree ofexperience is necessary to properly adjust perforators using flexing ordeflectible bed roll blades.

The stationary anvil-mounted blades, sometimes referred to as anvilblades, of the present invention are mounted in the anvil so that theycan be controllably displaced when contact is made with the rotating bedroll blades. The present invention discloses various ways in which theanvil blade can be mounted to exhibit the limited amount of displacementnecessary to perform a good perforation and yet give blade lifecomparable to or better than that which is presently experienced withcommercial perforators.

By mounting the anvil blade in an elastomeric material it will respondin more than one plane, therefore allowing the blade to exhibit degreesof freedom, in at least two planes, which greatly reduces thecriticality of setting-up and adjusting the rotating bed roll blade withthe stationary anvil blade. Moreover, such freedom of movement will inmost instances obviate the need of hollow ground blades which areexpensive to produce and maintain.

Another benefit derived for mounting the anvil blade with two or moredegrees of freedom is that more uni form blade wear and a more lengthyblade life is achieved.

A further advantage provided by mounting the anvil block withelastomeric material is that quieter operation is achieved as themetal-to-metal contact of the perforating blades is effectivelydissipated.

The fundamental concept of this invention now makes it possible toprovide an elastic foundation for the cutting element mounted in the bedroll while the stationary cutting element can be mounted so that nodisplacement or deflection thereof occurs during normal operation.Moreover it is also possible to provide a resilient foundation for eachcutting element.

Another important feature of the present invention is the latitudeachieved in providing any desired response characteristics of theperforating blades. Known commercial perforators, for example the typeshown and described in the above mentioned United States patents, arehighly restricted in the options available for changing or varying theresponse time of the perforating blades. It can be accomplished in oneof two ways. The rotating bed roll blade can be lengthened to increasethe amount of flexure produced when it contacts the stationary anvilblade or the rotating bed roll blade can be made thicker to therebyreduce the deflection or flexure of the blade. The present invention canbe readily tuned to produce any response characteristics required by thespeed or the type of web being perforated. All that is necessary is toeither change the geometrical configuration of the elastomeric supportor to change the durometer hardness of the rubber. It should be realizedtherefore that changes in response time can be accomplished with aminimum of time and cost since the inventory of elastomeric material isimmeasurably more economical than providing an inventory of bladeshaving different lengths or thicknesses.

In accordance with the present invention the rotating bed roll bladescan be made much narrower, in the order of one half an inch, instead ofthe seven eighths or one inch that is presently used in commercialperforators. This is made possible by the present invention since therotating bed roll blade is firmly clamped and does not deflect withrespect to the bed roll. As a result of the perforating concept of thepresent invention, that is, providing a non-flexing bed roll blade, thebed roll does not require the rather complex surfaces and moresophisticated clamping arrangements of a flexing blade. Further therigidity of the bed roll is greatly improved because for a given bedroll diameter the cross sectional area and accordingly the moment ofinertia is increased permitting higher speed operation.

Other features and advantages of the present invention will be pointedout as the description of the preferred embodiment and some of itsmodifications are described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view, with a centralsection partly broken away, of a perforating apparatus incorporating thefeatures of the present invention,

FIG. 2 is a transverse section of FIG. 1 taken substan tially along theline 22 of FIG. 1,

FIG. 3 is an end view of the perforating structure shown in FIG. 1,illustrating in reduced scale, the gear train provided for driving thebed roll and the feed rolls,

FIG. 3A is an enlarged fragmentary portion of a perforating bed rollblade,

FIG. 4 is a greatly enlarged fragmentary portion of the anvil block,carrying the stationary blade, and the bed roll supporting the rotatingblade,

FIG. 5 is a fragmentary of FIG. 4 showing an alternative method ofmounting the anvil blade,

FIG. 6 is a similarly enlarged fragmentary portion of the anvil blockshowing the molded or extruded rubber insert and the anvil bladedisassembled,

FIG. 7 is a perspective of the anvil blade showing generally U-shapedrubber members mounted at each end of the anvil blade,

FIG. 7A is a diagrammatic perspective showing the orientation of theanvil and bed roll blades to produce point contact for progressiveshearing of the web,

Fit}. 8 is another modified form of the anvil block in which rubber, orother elastomeric material, may be molded and ground to provide a slotfor receiving the anvil blade,

FlG. 9 is yet another modified form of the anvil block wherein theelastomeric insert and the anvil blade are assembled and bonded to theanvil block,

FlG. lb is yet another modified form of assembling the anvil blade inthe anvil bloclt in which the elastomer is molded and bonded to theanvil blade and then pressed into the anvil bloclt slot,

FIG. ll is another modified form of mounting the anvil blade in theanvil block by utilizing precision strips of elastorner having one sidesupplied with adhesive backing firmly holding the strips to the anvilblock while the anvil blade is pressed in between the rubber strips,

HQ. 12 is still another modified form of mounting the anvil blade in theanvil block by providing a rubber insert or elastomeric insert adjacenttwo surfaces of the anvil blade,

FIG. 13 shows a modification wherein the anvil block is provided with alocating shoulder engaging the rear surface of the anvil blade,

H6. 14 shows yet another modified form in which rubber strips aremounted on opposed surfaces of the anvil blade and a circular rubberinsert makes engagement with the rear surface of the anvil blade,

FlG. l5 shows a modified form wherein the anvil blade and the anvilbloclt are provided with longitudinal semicircular grooves for receivingcomplementary shaped circular projections of the rubber inserts,

PKG. id is a modified form of the perforating appara tus of the presentinvention utilizing a square shaped bed roll blade, supported on anelastomeric insert,

FlG. 117 is an enlarged perspective of the bed roll blade of H6. to,

H6. 118 shows yet another manner of mounting the anvii blade in theanvil block which includes a sinosoidal or wave shaped spring engaged bythe rear surface of the anvil blade and rubber inserts on either side ofthe anvil blade,

FlG. H9 is a section taken substantially along line l9ll9 of FIG. lb,and

HG. Ell illustrates a modification wherein the anvil blade is mounted ona leaf spring.

DESCRlPTlON OF THE PREFERRED EMBODlMENT The perforating apparatus of thepresent invention is generally identified by the numeral 30 and itsmajor components include a transverse beam 32 carried by side plates 34and 36 that are in turn mounted on the frame of the rewinding or windingmachine (not shown). Rotatably supported between the side plates 34 and.336 is a bed roll 38 provided, as shown in FIG. 2, with a plurality ofequally circumferentially spaced slots 4b in which perforating blades 42are mounted. The web W is wrapped around the bed roll 38 and fedthereover by felt covered feed rolls 4d and 46 that are in pressureengagement with the bed roll 38 to insure that the web speed and thesurface speed of the bed roll 38 is substantially the same. The feedrolls 44 and 46 are provided with longitudinal indentations 48 forreceiving the projecting portion of the bed roll blades 32 to insuresmooth vibration free operation of the perforator. Adjusting means 5dare associated with each end of the feed rolls 44 and as for regulatingthe nip pressure that the feed rolls 44- and 46 establish with the bedroll 38.

The anvil beam 32, which is mounted between the side plates 34 and do,is adjustable transversely relative to the bed roll 38 by a mechanism 52which includes a wedge block 54 translatable by an adjusting stud 56having collars 57 that hold stud 56 against axial movement. Rotation ofthe stud 56 moves the wedge bloclts 54, which, depending upon thedirection of rotation of the stud 56, adjusts the anvil beam 32 towardor away from the bed roll 38. Each end of the beam 32 is rigidlyconnected to end plates 58 which are fitted in guideways formed in theend plates 34 and 36 to insure linear transverse movement of the beamstructure 32 relative to the bed roll 3%.

A shaft 60 has its ends rigidly connected to the end plate 58 and isdisposed parallel to the axis of the bed roll 38. On the shaft so aplurality of anvil blocks 62, taking the form of a bell crank having adepending lever arm 62a and an upwardly extending lever arm 62b, arerotatably mounted. The anvils 62 carry anvil blades 64 being located tocooperate with the bed roll blades 52 to effect transverse perforationof the web as it is moved past the anvil blades. Each of the dependinglever arms 62a has a stop button 66, taking the general form of aspherical projection, rigidly secured thereto which is engaged by ascrew 68 received in a threaded bore provided in the anvil beam 32. Thelever arm 62b is formed to provide a bored boss 7@ in which is disposeda spring 72 whose degree of compression is determined by adjustablestuds 74. threaded in the beam 32 and provided with lock nuts 76. Sincethe anvil block 62 is mounted for freedom of rotation on a shaft 60, theposition assumed by the anvil blade 64 is determined by the adjustmentof the screws 68, the end of which is in abutting engagement with thebuttons 66 on each anvil. The force supplied by the spring 72 determinesthe contact force between the buttons 66 and its associated screw 68. Asa consequence of this arrangement the forces resulting from theengagement of the rotating bed roll blades 42 with the anvil blade 64are in part resisted by the spring '72. Ruling out the presence of wadsor other obstructions the rubber insert 78 permits the anvil blade to beslightly displaced both sidewise and endwise when it is contacted by therotating bed roll blade, since these blades are adjusted with apredetermined amount of interference which is necessary to subject thepaper web to the shearing action necessary to produce the clean cutperforations. When a wad is carried by the web to the bed roll theamount of displacement to which the anvil blade 64 is subjected isgreater than can be accommodated by the rubber insert 78. Accordingly,under the circumstances the springs '72 are compressed due to theresulting counterclockwise rotation (as viewed in FIG. 2) of the anvilblock 62 permitting the obstruction or wad to pass without causing unduestress to the coacting blades 4-2 and 64.

As shown in FIG. 3, a gear train 80 including gears 82, keyed to theends of rolls l4 and 4d and a gear 84, keyed to the end of the bed roll38, is provided for establishing the speed relationship between therolls 44 and 46 and the bed roll 38 thereby insuring that theindentations 48 are in time with the bed roll blades 42.

The disclosed perforating apparatus also provides a mechanism forpositioning the anvil block 62 to a nonoperative position and such meansare generally indicated by the numeral 86. On the lower surface of theanvil beam 32 a plurality of air cylinders 855, corresponding in numberto the anvils 62, are mounted. On the end of each cylinder rod aspherical button MP is mounted and is engageable with the lower portionof the dependent lever arm 62a. Actuation of a conventional controlvalve (not shown) supplies pressure fluid to each of these cylinders 23%extending the rods thereby engaging the buttons W) with the dependinglever arms 62a. The anvil blocks 62 are accordingly rotated in acounterclockwise direction against the bias of the spring 72. The anvilblades 64 are thus drawn away from the bed roll 38. With the anvil block62 located in this position threading of the web or removingobstructions ocassioned by wrap ups or jams of any nature isfacilitated. In returning the machine to its operative position thecylinders 88 are vented to the atmosphere rendering the spring '72operative to retract the plungers of each cylinder.

According to the above described arrangement it can be seen that a web Wis supported on the bed roll 38 and it is provided with longitudinallyspaced transverse perforations when each bed roll blade 42 makes contactwith the stationary anvil blade 64.

To adjust the nip pressure that the rolls 4'4 and en establish with thebed roll 33 the adjusting means are provided. Since the adjusting means50 are identical in structure and function description of one willsuffice for all. It should also be understood that each end of the rolls44 and 46 are provided with a journal received within bearings carriedby the adjusting means 50. Referring now to FIG. 2, it will be observedthat a bearing block 94% is provided for supporting the journals ofrolls 44 and 4-6. The bearing blocks are slidable along guides 96rigidly attached to the side plate 36. By means ofan adjusting screw 98,fixed against axial movement relative to the bearing blocks 94 bycollars 100, the bearing blocks and accordingly the rolls 44 and 46 canbe translated toward and away from the surface of the bed roll 38. Inthis manner, the nip pressure exerted by the feed rolls &4 and 46 on thebed roll 38 can be regulated.

Each bed roll blade 42 has its cutting edges formed to make aninterrupted out which consists of aligned linear shear cuts separated byuncut portions. The portion of the blade 42 shown in FIG. 3A producessuch cutting by providing substantially equally spaced slots 412ainterrupting the cutting edge 42b. Each blade is designed to providefour cutting edges before resharpening is required.

In accordance with the preferred arrangement of the present inventionthe perforating apparatus mounts the rotating bed roll blade so that itis not subject to flexure or deflection. All movement resulting from theblades coming in contact is produced by the anvil blade. FIG. 4illustrates, on greatly enlarged scale, one of the bed roll blades 42 incutting engagement with an anvil blade 64. As shown in FIG. 4, the web Woverlies the bed roll blades 42 which are carried in the slot 40 havinga planar back up surface 1W2 formed in the bed roll for backing up thetrailing side of the blade. As shown in FIG. 2, the bed roll includes aplurality of'equally circumfcrentially spaced slots 4t each having aplanar surface M2 for supporting the bed roll blades 42. The blades 42are clamped in position on the surface MP2 of the slot 4th by a clampingbar 1106 mounted to the bed roll by bolts W8 which are received intapped holes. The bed roll blade 42 is positioned on the surface MP2 sothat the intersection of its lower surface and its outer edge,identified by the numeral IMP, lies within the surface of the bed roll38. Due to the fact that the bed roll blade 42 defines an angle lessthan degrees with the radius of the bed roll, the blade provides aprojecting edge Elba extending beyond the surface of the bed roll forcooperation with the anvil blade 64.

In order to achieve progressive shearing action from one edge of eachblade 42 to the other, the anvil blades 654i are skewed slightly, asshown in FIG. 7A, so that the bed roll blades 42 make point contact withone edge of the anvil blade 64 and this point of contact travelsprogressively along the width of the anvil blades to produce theperforations.

As will be pointed out hereinafter, with reference to the variousembodiments shown in FIGS. 5-15 and lid and I9, the rubber insert 78 cancomprise either a unitary molded piece provided with a slot forreceiving the anvil blade, flat rubber strips or rubber inserts having aconfiguration keying the anvil blade to the anvil block. The rubberinsert may be press fitted into the anvil block, and the anvil blade maybe in turn press fitted into the rubber insert. The rubber insert may bebonded to the anvil block and have a slot dimensioned for press fittingthe anvil blade therein or the rubber insert may be bonded to the anvilblade and the unitary structure press fitted into the anvil block.Moreover, the rubber insert may be bonded to the anvil block and theanvil blade bonded to the rubber insert. If this procedure is followedthe anvil blade may be ground, while assembled in the anvil block, todefine the cutting edge.

Referring now to FIG. 5, there is shown another way in which the anvilblade and the rubber insert may be carried by the anvil block. In thiscase the anvil block 62 is provided with a slot generally indicated bythe numeral M4 in which is fitted, either by pressing or by bonding, arubber insert 78a. The insert 78a is gener ally of a U-shapedconfiguration in cross section thereby providing a slot in which theanvil blade n4 is fitted again either by bonding or pressing. It will benoted that the anvil blade 64 assumes a general vertical orientationpresenting one of its edges for engagement with the projecting edgelllltla of the bed roll blade 42.

FIG. 6 shows an arrangement which is in substantial respects similar tothat of FIG. 4 The rubber insert 78b may be molded or extruded, and, asin the case of the modification shown in FIG. 5, may be bonded to theanvil block 62. The anvil blade 64 can be press fitted into the slot116.

The structure of FIG. '7 shows the anvil blade 64 carrying generallyU-shaped rubber bands 78c on each end thereof. The bands 780 may bebonded to the anvilblade 64 which may then be press fitted into the slotof the anvil block 62. Alternatively the rubber inserts 780 may be pressfitted into the anvil block slot IE4, and the anvil blade 54 pressfitted into the rubber inserts.

The modification of FIG. 8 is made by bonding a solid piece ofelastomeric material 7&1 into the anvil block slot 11 lid. The anvilblade receiving slot M6 is the ground to a size establishing a press titfor the anvil blade 64.

FIG. 9 is substantially similar to the arrangement as shown in FIG. 8with the exception that the anvil blade 6 and the rubber insert 78c arebonded, respectively, to the insert and to the anvil block 62. Thedotted line indicates the original size of the anvil blade 64 before itis ground to define the cutting edge 64a.

FIG. 11) shows yet another modified form of assembling the anvil blade64 into the anvil block 62. In this instance the rubber insert 78f isbonded to the anvil blade 64 and they are inserted as a unit into theslot 114.

In FiG. 11 the slot 114 of the anvil block 62 is lined with rubberstrips collectively identified by the numeral 1 15. The strips may beprovided with an adhesive backing and may be of selective durometerhardnesses in order to give the anvil blade 64 response characteristicswhich will assure that the anvil blade is in the proper position whenthe successive bed roll blades 42 come in contact therewith to effectperforation of the web. For example if the anvil blade 64 were torespond in such a way that it does not assume the proper position toengage a successive bed roll blade 42, the cause may be that thehardness of the rubber is not sufficient to damp the forces imparted tothe anvil blade in the time available for the upcoming bed roll blade tocutting engagement with the full width of the anvil blade. The slot 114is formed with cavities 117 which allow an expanison space for therubber strips when they are under stress.

FIG. 12 shows an arrangement for mounting the anvil blade 64 so that anelastomeric insert 78g is in contact with the rear and the upper surfaceof the anvil blade 64.. When the bed roll blade 42 makes contact withthe anvil blade 64 it is moved rearwardly and slightly up wardly againstthe inherent pliability of the rubber insert 78g. Upward movement of theanvil blade 64 enables paper dust to gather thereunder causing progressive upward relocation of the blade 64 which may result in imperfect orlost perforations. To preclude such a condition a series of grooves114a, preferably of sawtooth configuration are formed in the lowersurface of the slot 114.

FIG. 13 shows another way in which the anvil blade 64 may be mounted inthe anvil block 62. In this embodiment the anvil block 62 is providedwith a locating shoulder 118 against which the rear surface of the anvilblade 64 is located. Rubber strips 120, which again may be of the sameor different durometer hardnesses, are inserted in the anvil block oneither side of the anvil blade 64. The locating shoulder 118 and thewidth of the rubber strips 120 define cavities 122 which accommodatedisplacement of the rubber strips during the time the anvil blades 64encounters the shock loads produced by contact with the rotating bedroll blades 42. By providing the locating shoulder 118 the anvil blade64 is held against rearward movement but rocking of the blade 64 occursby virtue of the rubber strips 121).

The modification of FIG. 14 is functionally similar to that shown anddescribed in FIG. 13 with the exception that the slot 1 14 in the anvilblock 62 carries a solid circular elastomeric element 124 which isengaged by the rearward surface of the anvil blade 64. Also, as in thecase of the arrangement shown in FIG. 13, cavities 122a are provided toallow displacement of the elastomeric material when the anvil bladecomes under the influence of the bed roll blades 42. The rubber strips120 can be made of the same or of different durometer hardncssesdepending upon the response characteristics desired. Further theembodiment of FIG. 14 permits the anvil blade 64 to move inwardly towardthe circular rubber insert 124 when the bed roll blades 42 make contactwith the anvil blade 64. In the case of FIG. 13, such action is notpossible since the locating shoulder 118 prevents any inward movement ofthe anvil blade 64.

The embodiment of FIG. 15 generally follows the constructionalarrangement of FIG. 14 with the exception that the rubber strips 120 areformed with semicircular, longitudinally extending, ribs 1200 which arereceived in grooves formed in the anvil blade 64 and in the anvil block62. The ribs 120a fulfill a function of keying the anvil blade 64 to theanvil block and therefore absorb a portion of shear forces the anvilblade 64 is subjected to when it comes in contact with the bed rollblades 42. This of course increases the stiffness of the system byreducing the displacement of the anvil blade by the bed roll blades 42and resists any permanent dislocation of the anvil blade 64.

The concept of the present invention providing perforating blades whichdo not flex or deflect makes it possible to provide a rigidnon-displaceable anvil blade coacting with a displaceable bed rollblade. The concept of the present invention is also applicable to aperforating system wherein the stationary anvil blade and the rotatingbed roll blade are each supported in elasto meric material. Referringnow to FIG. 16 there will be seen a perforating apparatus in which thebed roll blade is mounted for displacement while the anvil blade isrigid with respect to the anvil block. The anvil block 62 has rigidlymounted therein the anvil blade 64. The bed roll 38, rotatable in thedirection of the arrow, is provided with a perforating bar 126 beinggenerally a rectangular bar. The bar 126 is shown in large perspectivein FIG. 17 and it will be observed that it is of substantiallyrectangular cross section having undercut bands 128 extending on allfour sides. By making the bar in this manner all four edges may be usedbefore regrinding is necessary. The bed roll is formed with the cavity130 in which is fitted a mass of elastomeric material 132. Overlying theelastomeric material is a thin metal plate 134 upon which is seated theperforating bar 126. The perforating bar is held in place by theclamping bar 106 which is attached to the bed roll by screws 108. Thecavity 130 is provided with expansion chambers 136 for allowingextrusion of the elastomer 132 when it is subjected to compressive forcegenerated when the perforating bar 126 makes contact with the anvilblade 64. This is necessary since the elastomer is volumetricallyincompressible and requires freedom of displacement so that it mayfulfill the function of a resilient foundation, When one set of edges ofthe perforating bar 126 is worn, the bar can be positioned to present anew sharpened edge to the anvil blade 64.

The modified form of the perforator shown in FIGS. 18 and 19 combinesthe benefits derived from utilizing elastomeric inserts on either sideof the anvil blade 64 and a wave or sinusoidal spring backing up theanvil blade. Referring first to FIG. 18 it will be seen that the anvilblock 62 is provided with a T slot 139 in one leg of which is mounted awave spring 140 which provides a flexible foundation for the inner edge64!; of the anvil blade 64. The anvil blade is further resilientlyrestrained against transverse movement by rubber strips 142, which maybe of the same or different durometer hardnesses, to achieve a desireddynamic response. By this construction the force that the anvil blade 64is subjected to when it makes contact with the bed roll blade 42 is inpart absorbed by the wave spring 140 and the rubber strips 142. Therubber strips also permit the blade 64 to rock in response in contactwith the bed roll blade 42.

The final embodiment of the present invention is shown in FIG. 20. Theanvil blade identified by numeral 144 is rigidly attached, preferably bywelding, to a leaf spring 146 which in turn is clamped to the anvilblock 62 by a bar 148 held in place by fasteners 150. The anvil block 62is formed with a projection 152 having an inclined surface 154supporting a complementary inclined surface formed on the anvil blade144. It should be noted that the spring 146 assumes a nonlinearconfiguration causing the spring to be preloaded thereby holding theanvil blade 144 in forceable contact with the surface 154. The degree ofspring force can be regulated by selecting the thickness of the spring146. Such preloading is necessary to insure that the anvil blade 144will remain in contact with the bed roll blade 42 to produce acceptableperforations.

Although the best mode contemplated for carrying out the presentinvention has been herein shown and described, it will be apparent thatmodification and variation may be made without departing from what isregarded to be the subject matter of the invention.

What is claimed is:

1. An apparatus for perforating thin, flexible sheet material such aspaper, plastic or foil, said apparatus being of the type comprising anormally stationary anvil, means for mounting an anvil blade on saidanvil, a bed roll mounting a rotary blade disposed at an acute angle toa radius of the roll so that only the leading edge of said rotary blademakes contact with an edge of said anvil blade, means for adjusting oneof said blades to establish a predetermined amount of interferencebetween said contacting blade edges, said means for mounting the anvilblade on said anvil comprising means forming an elongate slot in saidanvil, and a body of elastomeric material in said slot for resilientlysup porting two faces of said anvil blade, at least one face of saidbody of elastomeric material being unconfined along the extent of saidblade in order to accommodate sidewise displacement of said anvil bladerelative to said anvil when said rotary blade makes contact with saidanvil blade; the improvement wherein there is no metal to metal contactbetween said anvil and said anvil blade on the side of the anvil bladethat is urged sidewise toward the opposed wall of said anvil slot whensaid anvil blade is contacted by said rotary blade.

2. The apparatus of claim 1, wherein said body of elastomeric materialcomprises a rubber member formed to releasably retain said anvil blade.

3. An apparatus for performing thin flexible sheet material such aspaper, plastic or foil of the type comprising a normally stationaryanvil block having a slit therein, means mounting an anvil blade in saidanvil block slot, a rotary blade having one of its edges located to makecontact with an edge of said anvil blade, and means for adjusting one ofsaid blades to establish a predetermined amount of interference betweenthe edges thereof; the improvement comprising means supporting saidanvil blade on an elastomeric foundation for causing biasedmultidirectional displacement of said anvil blade when its edge iscontacted by the edge of the rotary blade to thereby maintain said edgesin forceable engagement thereby effecting perforation of the sheetmaterial, said anvil blade mounting means comprising a U-shaped rubberinsert in said slot formed to receive and retain said anvil blade.

4. The apparatus of claim 3, wherein said rubber insert is bonded insaid anvil block slot.

1. An apparatus for perforating thin, flexible sheet material such aspaper, plastic or foil, said apparatus being of the type comprising anormally stationary anvil, means for mounting an anvil blade on saidanvil, a bed roll mounting a rotary blade disposed at an acute angle toa radius of the roll so that only the leading edge of said rotary blademakes contact with an edge of said anvil blade, means for adjusting oneof said blades to establish a predetermined amount of interferencebetween said contacting blade edges, said means for mounting the anvilblade on said anvil comprising means forming an elongate slot in saidanvil, and a body of elastomeric material in said slot for resilientlysupporting two faces of said anvil blade, at least one face of said bodyof elastomeric material being unconfined along the extent of said bladein order to accommodate sidewise displacement of said anvil bladerelative to said anvil when said rotary blade makes contact with saidanvil blade; the improvement wherein there is no metal to metal contactbetween said anvil and said anvil blade on the side of the anvil bladethat is urged sidewise toward the opposed wall of said anvil slot whensaid anvil blade is contacted by said rotary blade.
 2. The apparatus ofclaim 1, wherein said body of elastomeric material comprises a rubbermember formed to releasably retain said anvil blade.
 3. An apparatus forperforming thin flexible sheet material such as paper, plastic or foilof the type comprising a normally stationary anvil block having a slittherein, means mounting an anvil blade in said anvil block slot, arotary blade having one of its edges located to make contact with anedge of said anvil blade, and means for adjusting one of said blades toestablish a predetermined amount of interference between the edgesthereof; the improvement comprising means supporting said anvil blade onan elastomeric foundation for causing biased multidirectionaldisplacement of said anvil blade when its edge is contacted by the edgeof the rotary blade to thereby maintain said edges in forceableengagement thereby effecting perforation of the sheet material, saidanvil blade mounting means comprising a U-shaped rubber insert in saidslot formed to receive and retain said anvil blade.
 4. The apparatus ofclaim 3, wherein said rubber insert is bonded in said anvil block slot.